All hail, great master! Grave sir, hail! I come
To answer thy best pleasure, be ’t to fly,
To swim, to dive into the fire, to ride
On the curled cloud. To thy strong bidding, task
Ariel and all his quality. (I.ii.)

These are Ariel’s first lines in the play, and they express his willingness to do whatever Prospero asks of him. Ariel indicates the impressive range of fantastic skills that he, as a spirit, possesses. What’s more, with the phrase “all his quality,” Ariel indicates that he also has a host of fellow spirits at his beck and call. In commanding Ariel, Prospero in fact commands a large sector of the spirit realm.

Is there more toil? Since thou dost give me pains,
Let me remember thee what thou hast promised,
Which is not yet performed me. (I.ii.)

In Act I, Ariel reminds Prospero that he only does the sorcerer’s bidding in order to gain his freedom, and not out of any real sense of loyalty or enjoyment. When Prospero arrived on the island, he liberated Ariel from a pine tree where the witch Sycorax had imprisoned him. Ariel then promised to work faithfully in Prospero’s service for a year to repay him. Now that a year (or more) has passed, Ariel wants Prospero to uphold his end of the bargain. The fact that Ariel feels worried about Prospero’s honesty may indicate that their relationship has not been without tension.

Full fathom five thy father lies.
Of his bones are coral made;
Those are pearls that were his eyes;
Nothing of him that doth fade
But doth suffer a sea-change
Into something rich and strange. (I.ii.)

Ariel sings this song to Ferdinand in Act I. The song confuses and saddens Ferdinand. The song confuses him because he cannot discern the source of the song, since Ariel remains hidden. The song saddens him because it convinces him that his father has died. The song’s emphasis on transformation (i.e., “sea-change”) is also significant. Not only does the song tap into the play’s larger theme of changing relationships, but it also references the island’s fluid, illusory nature.

You are three men of sin, whom destiny,
That hath to instrument this lower world
And what is in ’t, the never-surfeited sea
Hath caused to belch up you, and on this island
Where man doth not inhabit, you ‘mongst men
Being most unfit to live. I have made you mad. (III.iii.)

Just after a host of spirits has presented Alonso, Antonio, and Sebastian with a sumptuous banquet, Ariel appears to the men in the terrifying form of a harpy. A harpy is a rapacious monster from classical mythology. Harpies are hybrid creatures, composed of a woman’s head and torso as well as a bird’s wings and claws. This frightening vision is intended, as Ariel declares, to drive the men mad.

Your charm so strongly works ’em
That, if you now beheld them, your affections
Would become tender. (V.i.)

With these lines from the final act, Ariel attempts to convince Prospero that his conjuring tricks have had the desired effect on his enemies. Ariel appears to take pity on the castaways, and he even tells Prospero that his own affections would be tender “were [he] human.” However, Ariel’s freedom is also conditional upon Prospero ceasing with tricks and reconciling with his enemies. In this sense, Ariel’s words seek to manipulate Prospero in the interest of securing his own freedom.